Those reformed show spirit (5)
I believe the answer is:
'spirit' is the definition.
(I've seen this before)
'those reformed' is the wordplay.
'reformed' is an anagram indicator.
'those' anagrammed gives 'ETHOS'.
'show' is the link.
(Other definitions for ethos that I've seen before include "Characteristic spirit of a community - for those" , "Distinctive attitudes of a people" , "Cultural spirit" , "Characteristic attitude" , "Culture, way of life" .)